This thesis argues that American exceptionalism is a necessary, but insufficient, way of reading U.S. foreign policy. Exceptionalism is employed by different ideologists in different ways and in differing contexts. This thesis employs the contextualist methodology of Quentin Skinner to challenge proleptic, static understandings of American exceptionalism and, in doing so, uncovers American grand strategy as a keenly contested ideological battleground. In each constituent case study, the thesis identifies the ideological innovators of American strategic policy and the key moments of ideological innovation, and examines why ideological innovations became conventional, or not. The analysis proceeds with an introduction to the composition of grand strategy, continues with an examination of Quentin Skinner’s version of Cambridge School contextual analysis, and then places Skinnerian contextualism within the broader framework of International Relations theory. This analysis illustrates the methodological advantage of Skinnerian contextualism, which allows the reconstruction of the context in which past generations of ideological innovators operated and conceived of the world and the place of the United States within it. This specific type of analysis demonstrates ideological innovation in practice at four pivotal moments in American foreign policy: first, the emergence of containment as the cornerstone of the Truman Doctrine at the outset of the Cold War; second, détente and the supposed injection of realism into American foreign policy; third, President Clinton’s strategy of enlargement and the place of American exceptionalism in the aftermath of the Cold War; and, fourth, the Bush Doctrine and the interaction between American exceptionalism and neoconservatism. The thesis concludes by stressing the particularities of historical context, having demonstrated that, although exceptionalism has rarely been the only causal dynamic of American grand strategy, it has consistently provided the context with which innovating ideologists have been required to engage in order to create their own version of grand strategy.